Bellows for a compensator and associated compensator and method for producing a bellows
1. Field of the Invention
The invention relates to a bellows for a compensator as an elastic connection between two duct connection pieces which are arranged [lacuna] from each other in the longitudinal direction, and to a corresponding compensator using a bellows of this type according to the preamble of claim 1 and 20, and to a method for producing a bellows according to claim 25.
2. Description of Related Art
Compensators of this type having a bellows structure which is known in accordance with the preamble of claim 1 are used in particular for decoupling structure-borne noise and/or as an expansion-compensating means in ventilation ducts in air conditioning technology. They are also suitable for compensating for thermal expansions and installation inaccuracies.
Ducts, in particular ventilation ducts in air conditioning technology, may, as is known, have different cross sectional shapes. EP 0 148 286 A1 basically discloses a flange connection for the mutual fastening of duct subsections, which are essentially rectangular in cross section, for air-conditioning duct systems, in which case the flange connection known therefrom can be used both for the installation of fixed duct walls and for the installation of an elastic wall so as to form a bellows.
EP 0 282 608 A1 discloses a duct structure which is comparable with regard to the flange profile, but is suitable for duct pieces which are circular in cross section. In this case too, the flange connection known therefrom can be used with fixed duct walls, which generally consist of sheet metal, or with the insertion of an elastic wall material to form a bellows.
DE 41 40 870 A1 which forms the generic type has disclosed a duct connecting piece in the form of a compensator. In the longitudinal direction or direction of attachment, the compensator contains two encircling flange structures which are spaced apart in the longitudinal direction or direction of attachment and are oriented transversely with respect to the longitudinal direction, said flange structures being used to enable the compensator to be fixedly connected to a next duct piece. The flange structure may be rectangular or generally polygonal in plan view, but in a modified embodiment may also be circular or oval. In this case, the bellows consists of a duct skin which is produced from a material web in an appropriate size and is tightly joined together to form a tube which is closed in the circumferential direction. Furthermore, both a sealing lip and a securing section are also formed on the duct skin, in order thereby to secure the duct skin in a suitable manner in a bead-shaped depression of the flange profiles.
Although these structures are in principle well-established, it is the object of the present invention to provide bellows and a compensator which have been improved further with respect to said structures, and to provide a corresponding process for producing bellows of this type.
According to the invention, the object is achieved with regard to the bellows [lacuna] features specified according to claim 1 and, with regard to the compensator, according to claim 21 and, with regard to a method of producing a bellows according to the invention, according to claim 25. Advantageous refinements are specified in the subclaims.
The bellows according to the invention and the compensator according to the invention have clear advantages over the prior art.
According to the invention, the bellows now consists not only of a flexible or elastic duct skin, but is designed as a double-walled hollow chamber system. In this case, the bellows according to the invention can be referred to in the widest sense as tubular, on account of its double wall system, even before it is used and before it is fitted in a compensator.
The bellows according to the invention and the compensator according to the invention have the surprising and advantageous effect that on account of its tubular, double-walled design, the bellows does not form any pronounced depressions or any material overlaps in its bending regions when it buckles at the corners of a square, rectangular or polygonal compensator, but also in the case of a compensator which is round or partially round in cross section. In the case of structures according to the prior art, this results in the formation of virtually dead corners, angles and pockets through which air, if used, does not flow or virtually no longer flows. In contrast, instead of the pronounced depressions or overlaps of the bellows material which occur in conventional structures according to the prior art and include the formation of shielded or dead zones and pockets, in the case of the bellows according to the invention the wall material lying on the inside is, if the need arises, deformed by static compressions, and the outer bellows material by static expansions in such a manner that deformations of a comparatively large size are produced and are formed over a large area comparable to gentle hills and valleys. This reliably avoids it being possible for the bellows material to be so distorted that it protrudes in a comparatively pronounced manner into the duct interior, through which air flows, partially overlaps with adjacent wall material and forms shielded dead corners and pockets through which the air basically flowing through the duct piece during use does not flow.
The bellows material according to the invention and the compensators according to the invention are therefore particularly suitable also for use in critical regions, for example in clinics where the intention is to reliably prevent bacteria from being able to permanently settle and become lodged in such dead corners and pockets as are formed in the prior art.
Within the scope of further refinements, the bellows material according to the invention can have numerous additional advantages.
It has proven advantageous if the bellows material is, in its entire width, i.e. in other words in the fitted state, of double-walled design in the longitudinal direction of the compensator and preferably does not have any inner webs. As a result, the inner wall ensures maximum freedom for the deformations with respect to the outer wall, advantageously assisting in the resultant, abovementioned aims and advantages.
Furthermore, there are formed, preferably on the tubular bellows material, not only corresponding sealing lips and sealing projections which interact with corresponding sealing lips or sealing projections of an adjacent channel subsection (so as in general to ensure the tightest possible connection of the duct pieces to be connected to one another), but there are also provided, preferably on the bellows, further securing projections, for example securing lips. These can preferably be provided with a barbed strip or barbed lip via which the bellows formed in this manner can be inserted without any problem and without further assisting means or tools in a corresponding groove-shaped depression or bead, provided with an undercut, in the flange pieces and can thereby be connected fixedly to the flange pieces.
The bellows material can be produced from all suitable materials, for example from polymeric material, elastic and/or flexible material, elastomeric material. EDPM material or else other sorts of plastic, for example polyester, PVC, etc, are likewise suitable.
The bellows material can be manufactured from flame-resistant, ray-absorbing, noncombustible, acid proof, heat-deflecting and/or thermally stable material.
The bellows is preferably produced by extrusion. In this case, the bellows can simultaneously also be produced together with a flange piece by extrusion, so that an additional connection of the thus formed bellows to flange pieces is no longer necessary. Should the stiffness and hardness of the flange region extruded with it not be sufficient, then an additional part used for reinforcing purposes, for example a metal flange piece or a plastic flange piece, may possibly also be attached and connected here to the flange leg.
In this case, preferably in the case of a flange section extruded together with a bellows, there can be cut in or punched out at intervals along the longitudinal side of the flange extruded with it, corresponding to the size of the compensator to be dimensioned, transverse recesses at corresponding intervals, in order to pivot the bellows together with the flange, for example through 90xc2x0 with respect to each other, at these points. Suitable corner pieces, for example made of plastic or of steel comparable to the other corner pieces used, can then be inserted at the thus formed corner regions. Said corner pieces may, for example, be correspondingly plugged in or clipped in, in particular if there are formed on the flange pieces extruded with it corresponding counter recesses, i.e. grid-type [sic] depressions or grid-type [sic] projections which make possible the desired, fixed connection to the corner piece.
Both in the last-mentioned case, but also in the formation of a securing lip on the bellows, it is likewise possible to use different materials in the bellows, which is thus of integral design. In terms of manufacturing, provision may be made here that, in particular in the region of [sic] the securing lip orxe2x80x94if the bellows is equipped at the same time with a flange sectionxe2x80x94this flange section is produced with a significantly harder material than the rest of the remaining bellows material. A xe2x80x9ccoextrusion processxe2x80x9d is conventionally also mentioned here, said process making it possible to produce a plastic part having a different material composition and, for example, hardness via two extruder dies.
Further advantageous effects can be obtained, particularly in the fitted state, by the cavity being filled with suitable materials, for example sheet-like materials, such as woven inserts, wire meshes, rubber mats, plastic lattices etc., or, for example, is stuffed or filled by other, tear-resistant materials.
In general, the hollow chamber system of the bellows can be filled with reinforcing, heat-insulating and/or sound-absorbing materials or else with materials which bring about an overall increase and improvement in the stability and/or load-bearing capacity of the bellows.
It is likewise possible to fill the hollow chamber, i.e. the double wall system of the bellows, with materials in the form of granules, for example styropor beads, quartz materials, metallic powder or similar materials.
Finally, materials used for the security against tearing and for the strength can additionally be inserted not only into the hollow chamber system, but, for example, reinforcing materials can also be incorporated into the bellows material during the extrusion or general production process.
In order to increase the strength against tearing, i.e. in particular with regard to the tensile stress possibly acting in the longitudinal direction of a compensator formed in this manner, provision may be made for a woven insert or other reinforcing insert to be inserted at the same time, for example in the bellows, preferably in the hollow chamber system, which insert is preferably nonextensible, with the consequence that once the fitted state has been reached, the edge of the reinforcing insert is clamped at the opposite end sections of the double-walled bellows system, with the result that the tensile forces are absorbed and supported via the reinforcing insert.
Finally, the bellows may also be provided [sic] by the introduction of fins preferably running in the longitudinal direction of the compensator (i.e. transversely with respect to the direction of extrusion) during extrusion, in order thereby to make the bellows material, and therefore the compensator in its longitudinal direction, even more stable, since a limitation on expansion is obtained thereby. Instead of the fins, steel elements or spring steel elements can be incorporated corresponding to the direction or connected in another manner to the bellows material in order to obtain this limitation on expansion.
The invention will be explained below with reference to exemplary embodiments, in which in detail: